1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to an image forming apparatus that includes a single storage to manage the lifetimes of components (such as developing units and photosensitive media) included in an integrated developing unit in the image forming apparatus.
2. Description of the Related Art
FIG. 1 illustrates the structure of a conventional image forming apparatus including a storage in each of a plurality of developing units. Referring to FIG. 1, a conventional electrophotographic color image forming apparatus 100 includes a developing unit 110, photosensitive media 145Y, 145M, 145C, and 145K, an optical scanning unit 150, an intermediate transfer belt 155, first transfer rollers 157Y, 157M, 157C, and 157K, a second transfer roller 160, and a fusing unit 165 within a case 101. In addition, the conventional electrophotographic color image forming apparatus 100 includes a paper feed cassette 105 containing paper P, a pickup roller 167 picking up paper P from the paper feed cassette 105, a paper feed roller 169 aligning and feeding paper P, first and second feed rollers 172 and 174 feeding paper P that has an image fused onto it, and a discharge roller 176 discharging the printed paper P from the case 101 onto a discharge tray 103.
The developing unit 110 includes four developing devices 112Y, 112M, 112C, and 112K. The developing devices are cartridge type devices which are replaced with new ones when developer, or toner, is depleted. Sequentially from the bottom of the case 101, the four developing devices 112Y, 112M, 112C, and 112K contain yellow (Y), magenta (M), cyan (C) and black (K) toners, respectively.
The developing devices 112Y, 112M, 112C, and 112K of the developing unit 110 include developing rollers 113Y, 113M, 113C, and 113K, respectively, to supply toner to the four photosensitive media 145Y, 145M, 145C, and 145K, respectively, which are installed within the case 101 separate from the developing devices 112Y, 112M, 112C, and 112K. To supply toner to the photosensitive media 145Y, 145M, 145C, and 145K, developing bias is applied to the developing rollers 113Y, 113M, 113C, and 113K. The outer circumferences of the respective photosensitive media 145Y, 145M, 145C, and 145K face the intermediate transfer belt 155.
The optical scanning unit 150 includes four optical scanners 151Y, 151M, 151C, and 151K corresponding to the photosensitive media 145Y, 145M, 145C, and 145K, respectively. The optical scanners 151Y, 151M, 151C, and 151K scan light beams corresponding to Y, M, C, and K color image information onto the photosensitive media 145Y, 145M, 145C, and 145K, respectively. Laser scanning units (LSUs) using a laser diode as a light source may be used as the optical scanners 151Y, 151M, 151C, and 151K.
The first transfer rollers 157Y, 157M, 157C, and 157K are positioned to face the photosensitive media 145Y, 145M, 145C, and 145K, respectively, with the intermediate transfer belt 155 interposed therebetween. The second transfer roller 160 is positioned to face the intermediate transfer belt 155.
As shown in FIG. 1, integrated structures A, B, C, and D are implemented for colors K, C, M, and Y, respectively. The integrated structures A, B, C, and D include-storages 130K, 130C, 130M, and 130Y, respectively. Alternatively, although not shown, the photosensitive media 145Y, 145M, 145C, and 145K and the developing devices 112Y, 112M, 112C, and 112K may be implemented in 8 separate structures including 8 storages. Each of the storages 130K, 130C, 130M, and 130Y may be a customer replaceable unit monitor (CRUM) and store information such as the manufacturing date, the serial number, the manufacturing company, the lifetime, and the amount of residual toner in the developing unit 110. The information is provided to a user at a predetermined time.
Such conventional image forming apparatuses have problems. For example, since a storage is installed in each of a plurality of developing devices, the price of the image forming apparatus increases. In addition, since a plurality of storages are installed, the probability of malfunction is high, and, therefore, reliability and processing speed are low, as a whole.
Accordingly, there is a need for an image forming apparatus with an improved storage to increase the reliability and processing speed of the apparatus.